[PATCH AUTOSEL 6.14 552/642] net-sysfs: remove rtnl_trylock from queue attributes

Sasha Levin
2025-05-05T22:36:33Z

From: Antoine Tenart <atenart@kernel.org>

[ Upstream commit b0b6fcfa6ad8433e22b050c72cfbeec2548744b9 ]

Similar to the commit removing remove rtnl_trylock from device
attributes we here apply the same technique to networking queues.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
Link: https://patch.msgid.link/20250204170314.146022-5-atenart@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/core/net-sysfs.c | 147 ++++++++++++++++++++++++++-----------------
1 file changed, 89 insertions(+), 58 deletions(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 07cb99b114bdd..77465dc3cd648 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1244,9 +1244,11 @@ static int net_rx_queue_change_owner(struct net_device *dev, int num,
*/
struct netdev_queue_attribute {
struct attribute attr;
- ssize_t (*show)(struct netdev_queue *queue, char *buf);
- ssize_t (*store)(struct netdev_queue *queue,
- const char *buf, size_t len);
+ ssize_t (*show)(struct kobject *kobj, struct attribute *attr,
+ struct netdev_queue *queue, char *buf);
+ ssize_t (*store)(struct kobject *kobj, struct attribute *attr,
+ struct netdev_queue *queue, const char *buf,
+ size_t len);
};
#define to_netdev_queue_attr(_attr) \
container_of(_attr, struct netdev_queue_attribute, attr)
@@ -1263,7 +1265,7 @@ static ssize_t netdev_queue_attr_show(struct kobject *kobj,
if (!attribute->show)
return -EIO;

- return attribute->show(queue, buf);
+ return attribute->show(kobj, attr, queue, buf);
}

static ssize_t netdev_queue_attr_store(struct kobject *kobj,
@@ -1277,7 +1279,7 @@ static ssize_t netdev_queue_attr_store(struct kobject *kobj,
if (!attribute->store)
return -EIO;

- return attribute->store(queue, buf, count);
+ return attribute->store(kobj, attr, queue, buf, count);
}

static const struct sysfs_ops netdev_queue_sysfs_ops = {
@@ -1285,7 +1287,8 @@ static const struct sysfs_ops netdev_queue_sysfs_ops = {
.store = netdev_queue_attr_store,
};

-static ssize_t tx_timeout_show(struct netdev_queue *queue, char *buf)
+static ssize_t tx_timeout_show(struct kobject *kobj, struct attribute *attr,
+ struct netdev_queue *queue, char *buf)
{
unsigned long trans_timeout = atomic_long_read(&queue->trans_timeout);

@@ -1303,18 +1306,18 @@ static unsigned int get_netdev_queue_index(struct netdev_queue *queue)
return i;
}

-static ssize_t traffic_class_show(struct netdev_queue *queue,
- char *buf)
+static ssize_t traffic_class_show(struct kobject *kobj, struct attribute *attr,
+ struct netdev_queue *queue, char *buf)
{
struct net_device *dev = queue->dev;
- int num_tc, tc;
- int index;
+ int num_tc, tc, index, ret;

if (!netif_is_multiqueue(dev))
return -ENOENT;

- if (!rtnl_trylock())
- return restart_syscall();
+ ret = sysfs_rtnl_lock(kobj, attr, queue->dev);
+ if (ret)
+ return ret;

index = get_netdev_queue_index(queue);

@@ -1341,24 +1344,25 @@ static ssize_t traffic_class_show(struct netdev_queue *queue,
}

#ifdef CONFIG_XPS
-static ssize_t tx_maxrate_show(struct netdev_queue *queue,
- char *buf)
+static ssize_t tx_maxrate_show(struct kobject *kobj, struct attribute *attr,
+ struct netdev_queue *queue, char *buf)
{
return sysfs_emit(buf, "%lu\n", queue->tx_maxrate);
}

-static ssize_t tx_maxrate_store(struct netdev_queue *queue,
- const char *buf, size_t len)
+static ssize_t tx_maxrate_store(struct kobject *kobj, struct attribute *attr,
+ struct netdev_queue *queue, const char *buf,
+ size_t len)
{
- struct net_device *dev = queue->dev;
int err, index = get_netdev_queue_index(queue);
+ struct net_device *dev = queue->dev;
u32 rate = 0;

if (!capable(CAP_NET_ADMIN))
return -EPERM;

/* The check is also done later; this helps returning early without
- * hitting the trylock/restart below.
+ * hitting the locking section below.
*/
if (!dev->netdev_ops->ndo_set_tx_maxrate)
return -EOPNOTSUPP;
@@ -1367,18 +1371,21 @@ static ssize_t tx_maxrate_store(struct netdev_queue *queue,
if (err < 0)
return err;

- if (!rtnl_trylock())
- return restart_syscall();
+ err = sysfs_rtnl_lock(kobj, attr, dev);
+ if (err)
+ return err;

err = -EOPNOTSUPP;
if (dev->netdev_ops->ndo_set_tx_maxrate)
err = dev->netdev_ops->ndo_set_tx_maxrate(dev, index, rate);

- rtnl_unlock();
if (!err) {
queue->tx_maxrate = rate;
+ rtnl_unlock();
return len;
}
+
+ rtnl_unlock();
return err;
}

@@ -1422,16 +1429,17 @@ static ssize_t bql_set(const char *buf, const size_t count,
return count;
}

-static ssize_t bql_show_hold_time(struct netdev_queue *queue,
- char *buf)
+static ssize_t bql_show_hold_time(struct kobject *kobj, struct attribute *attr,
+ struct netdev_queue *queue, char *buf)
{
struct dql *dql = &queue->dql;

return sysfs_emit(buf, "%u\n", jiffies_to_msecs(dql->slack_hold_time));
}

-static ssize_t bql_set_hold_time(struct netdev_queue *queue,
- const char *buf, size_t len)
+static ssize_t bql_set_hold_time(struct kobject *kobj, struct attribute *attr,
+ struct netdev_queue *queue, const char *buf,
+ size_t len)
{
struct dql *dql = &queue->dql;
unsigned int value;
@@ -1450,15 +1458,17 @@ static struct netdev_queue_attribute bql_hold_time_attribute __ro_after_init
= __ATTR(hold_time, 0644,
bql_show_hold_time, bql_set_hold_time);

-static ssize_t bql_show_stall_thrs(struct netdev_queue *queue, char *buf)
+static ssize_t bql_show_stall_thrs(struct kobject *kobj, struct attribute *attr,
+ struct netdev_queue *queue, char *buf)
{
struct dql *dql = &queue->dql;

return sysfs_emit(buf, "%u\n", jiffies_to_msecs(dql->stall_thrs));
}

-static ssize_t bql_set_stall_thrs(struct netdev_queue *queue,
- const char *buf, size_t len)
+static ssize_t bql_set_stall_thrs(struct kobject *kobj, struct attribute *attr,
+ struct netdev_queue *queue, const char *buf,
+ size_t len)
{
struct dql *dql = &queue->dql;
unsigned int value;
@@ -1484,13 +1494,15 @@ static ssize_t bql_set_stall_thrs(struct netdev_queue *queue,
static struct netdev_queue_attribute bql_stall_thrs_attribute __ro_after_init =
__ATTR(stall_thrs, 0644, bql_show_stall_thrs, bql_set_stall_thrs);

-static ssize_t bql_show_stall_max(struct netdev_queue *queue, char *buf)
+static ssize_t bql_show_stall_max(struct kobject *kobj, struct attribute *attr,
+ struct netdev_queue *queue, char *buf)
{
return sysfs_emit(buf, "%u\n", READ_ONCE(queue->dql.stall_max));
}

-static ssize_t bql_set_stall_max(struct netdev_queue *queue,
- const char *buf, size_t len)
+static ssize_t bql_set_stall_max(struct kobject *kobj, struct attribute *attr,
+ struct netdev_queue *queue, const char *buf,
+ size_t len)
{
WRITE_ONCE(queue->dql.stall_max, 0);
return len;
@@ -1499,7 +1511,8 @@ static ssize_t bql_set_stall_max(struct netdev_queue *queue,
static struct netdev_queue_attribute bql_stall_max_attribute __ro_after_init =
__ATTR(stall_max, 0644, bql_show_stall_max, bql_set_stall_max);

-static ssize_t bql_show_stall_cnt(struct netdev_queue *queue, char *buf)
+static ssize_t bql_show_stall_cnt(struct kobject *kobj, struct attribute *attr,
+ struct netdev_queue *queue, char *buf)
{
struct dql *dql = &queue->dql;

@@ -1509,8 +1522,8 @@ static ssize_t bql_show_stall_cnt(struct netdev_queue *queue, char *buf)
static struct netdev_queue_attribute bql_stall_cnt_attribute __ro_after_init =
__ATTR(stall_cnt, 0444, bql_show_stall_cnt, NULL);

-static ssize_t bql_show_inflight(struct netdev_queue *queue,
- char *buf)
+static ssize_t bql_show_inflight(struct kobject *kobj, struct attribute *attr,
+ struct netdev_queue *queue, char *buf)
{
struct dql *dql = &queue->dql;

@@ -1521,13 +1534,16 @@ static struct netdev_queue_attribute bql_inflight_attribute __ro_after_init =
__ATTR(inflight, 0444, bql_show_inflight, NULL);

#define BQL_ATTR(NAME, FIELD) \
-static ssize_t bql_show_ ## NAME(struct netdev_queue *queue, \
- char *buf) \
+static ssize_t bql_show_ ## NAME(struct kobject *kobj, \
+ struct attribute *attr, \
+ struct netdev_queue *queue, char *buf) \
{ \
return bql_show(buf, queue->dql.FIELD); \
} \
\
-static ssize_t bql_set_ ## NAME(struct netdev_queue *queue, \
+static ssize_t bql_set_ ## NAME(struct kobject *kobj, \
+ struct attribute *attr, \
+ struct netdev_queue *queue, \
const char *buf, size_t len) \
{ \
return bql_set(buf, len, &queue->dql.FIELD); \
@@ -1613,19 +1629,21 @@ static ssize_t xps_queue_show(struct net_device *dev, unsigned int index,
return len < PAGE_SIZE ? len : -EINVAL;
}

-static ssize_t xps_cpus_show(struct netdev_queue *queue, char *buf)
+static ssize_t xps_cpus_show(struct kobject *kobj, struct attribute *attr,
+ struct netdev_queue *queue, char *buf)
{
struct net_device *dev = queue->dev;
unsigned int index;
- int len, tc;
+ int len, tc, ret;

if (!netif_is_multiqueue(dev))
return -ENOENT;

index = get_netdev_queue_index(queue);

- if (!rtnl_trylock())
- return restart_syscall();
+ ret = sysfs_rtnl_lock(kobj, attr, queue->dev);
+ if (ret)
+ return ret;

/* If queue belongs to subordinate dev use its map */
dev = netdev_get_tx_queue(dev, index)->sb_dev ? : dev;
@@ -1636,18 +1654,21 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue, char *buf)
return -EINVAL;
}

- /* Make sure the subordinate device can't be freed */
- get_device(&dev->dev);
+ /* Increase the net device refcnt to make sure it won't be freed while
+ * xps_queue_show is running.
+ */
+ dev_hold(dev);
rtnl_unlock();

len = xps_queue_show(dev, index, tc, buf, XPS_CPUS);

- put_device(&dev->dev);
+ dev_put(dev);
return len;
}

-static ssize_t xps_cpus_store(struct netdev_queue *queue,
- const char *buf, size_t len)
+static ssize_t xps_cpus_store(struct kobject *kobj, struct attribute *attr,
+ struct netdev_queue *queue, const char *buf,
+ size_t len)
{
struct net_device *dev = queue->dev;
unsigned int index;
@@ -1671,9 +1692,10 @@ static ssize_t xps_cpus_store(struct netdev_queue *queue,
return err;
}

- if (!rtnl_trylock()) {
+ err = sysfs_rtnl_lock(kobj, attr, dev);
+ if (err) {
free_cpumask_var(mask);
- return restart_syscall();
+ return err;
}

err = netif_set_xps_queue(dev, mask, index);
@@ -1687,26 +1709,34 @@ static ssize_t xps_cpus_store(struct netdev_queue *queue,
static struct netdev_queue_attribute xps_cpus_attribute __ro_after_init
= __ATTR_RW(xps_cpus);

-static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
+static ssize_t xps_rxqs_show(struct kobject *kobj, struct attribute *attr,
+ struct netdev_queue *queue, char *buf)
{
struct net_device *dev = queue->dev;
unsigned int index;
- int tc;
+ int tc, ret;

index = get_netdev_queue_index(queue);

- if (!rtnl_trylock())
- return restart_syscall();
+ ret = sysfs_rtnl_lock(kobj, attr, dev);
+ if (ret)
+ return ret;

tc = netdev_txq_to_tc(dev, index);
+
+ /* Increase the net device refcnt to make sure it won't be freed while
+ * xps_queue_show is running.
+ */
+ dev_hold(dev);
rtnl_unlock();
- if (tc < 0)
- return -EINVAL;

- return xps_queue_show(dev, index, tc, buf, XPS_RXQS);
+ ret = tc >= 0 ? xps_queue_show(dev, index, tc, buf, XPS_RXQS) : -EINVAL;
+ dev_put(dev);
+ return ret;
}

-static ssize_t xps_rxqs_store(struct netdev_queue *queue, const char *buf,
+static ssize_t xps_rxqs_store(struct kobject *kobj, struct attribute *attr,
+ struct netdev_queue *queue, const char *buf,
size_t len)
{
struct net_device *dev = queue->dev;
@@ -1730,9 +1760,10 @@ static ssize_t xps_rxqs_store(struct netdev_queue *queue, const char *buf,
return err;
}

- if (!rtnl_trylock()) {
+ err = sysfs_rtnl_lock(kobj, attr, dev);
+ if (err) {
bitmap_free(mask);
- return restart_syscall();
+ return err;
}

cpus_read_lock();
--
2.39.5